Ncert Exercises & Solutions

1.36 Chlorine is prepared in the laboratory by treating manganese dioxide (MnO2) with aqueous hydrochloric acid according to the reaction

$4 {HCl}_{(aq)} + {MnO}_{2 (s)} \to 2 H_{2} O_{(l)} + {MnCl}_{2 (aq)} + {Cl}_{2 (2)}$

How many grams of HCl react with 5.0 g of manganese dioxide?

1 mol [55 + 2 × 16 = 87 g] ${MnO}_{2}$ reacts completely with 4 mol [4 × 36.5 = 146 g] of HCl.
5.0 g of MnO2 will react with

= $\frac{146 g}{87 g} x 5.0 g$ of HCl

= 8.4 g of HCl

Hence, 8.4 g of HCl will react completely with 5.0 g of manganese dioxide.